Magneto ignition systems for internal combustion engines are widely used for motorcycles and snowmobiles. The magneto ignition systems in use are generally adapted to operate in conventional fashion. The magneto, which is a type of electrical generator, induces a voltage in a primary winding which is inductively coupled to a secondary winding to form a step-up transformer. Initially, current is permitted to flow in the primary winding to build up an electrical field thereabout. When the field reaches a certain pre-selected value, the circuit through the primary winding is suddenly opened, resulting in the field collapsing and inducing a sparking voltage in the secondary winding.
More recently, capacitive discharge ignition systems have come into favor. In a capacitive discharge system, a capacitor is charged to a pre-selected voltage. The capacitor is then suddenly discharged through the primary winding of an output coil. A sparking voltage is induced in the secondary winding of the coil upon the build-up of the field about the primary winding as opposed to being induced upon the collapse of the field in the primary winding. One advantage of a capacitive discharge system is that the sparking voltage is obtained more rapidly than is the case in conventional ignition systems. This is advantageous in that by reaching a peak voltage sooner, there is more chance that the spark plug will fire because there is not sufficient time for leakage and dissipation of electrical energy about a fouled spark plug. Additional advantages occur in the permissible range of timing which is realized with a capacitive discharge system.
The present invention utilizes the primary circuit of a magneto (without the customary points and capacitor) as the power supply in a capacitive discharge ignition system.